The Human Genome Project (HGP) spurred a great increase in sequencing throughput and resulted in a corresponding drop in sequencing costs. In contrast to the 13 years and cost of nearly three billion US dollars, per genome sequencing costs have been reduced significantly—indeed two individual genomes have recently been completed (McGuire et al., Science 317:1687 (2007)). Personal genomes represent a paradigm shift in medical treatment for both patients and health care providers. By managing genetic risk factors for disease, health care providers can more readily practice preventative medicine and provide customized treatment. With large banks of completed genomes, drug design and administration can be more efficient, pushing forward the nascent field of pharmacogenomics.
Many conventional DNA sequencing technologies implement optoelectronic technique as a means to detect and/or discriminate an object by detecting light emitted from the object. A detecting apparatuses used in these technologies are often expensive and the efficiencies are not high.
Conventional methods are usually based on the measurement within a certain wavelength band where the light emitted from the object(s) being detected has the highest intensity. The measured intensity is then used to calculate the concentration or amount of the objects. Recently, detecting light emitted from a single object is becoming popular. For example, one may need to detect the fluorescent light emitted from a single dye molecule so as to, e.g., discriminate the molecule. The intensity of such a fluorescent light can be very low, such that conventional detecting apparatuses and methods are not suitable to detect such a weak light. Also, the sensitivity of analytical procedures such as flow cytometry and flow-cytometry-like microfluidic lab-on-a-chip device can be limited by the sensitivity of the light detector. Increasing the sensitivity of such procedures could allow them to detect materials present at relatively low levels which nonetheless may be of interest in, for example, diagnostic or research applications.
Moreover, in many conventional apparatuses, color filters are often used, allowing a portion of the emitted light within a certain wavelength band to pass through and blocking other portion of the emitted light. Therefore, the apparatuses are complicated and more space is needed. Besides, since part of the emitted light is blocked by the color filter, the number of photons reaching the light detector is reduced. This makes such conventional apparatuses and methods even less suitable for detecting and/or discriminating, e.g., object with weak emission.
Therefore, there is a need for an apparatus and a method to detect and/or discriminate an object, especially an object emitting light of low intensity such as a single dye molecule.